Urban Malaria

Integrated approaches are especially suited to malaria control programs based in urban areas. Although urban centers traditionally experience lower rates of malaria transmission than rural areas, the rapid increase in the world’s urban population has major implications for the epidemiology of malaria (Robert et al., 2003). This is particularly true in sub-Saharan Africa, the most rapidly urbanizing continent (United Nations, 1999). In 1900, 10 percent of Africans lived in an urban area, whereas today almost half of the population in sub-Saharan Africa lives in urban or suburban areas. This proportion is expected to continue to rise over the next 25 years.

In fact, many African cities have unique features that still favor the transmission of malaria. Unlike Western cities with their distinct patterns of land use, housing construction, public utilities, and social services, many African cities have no such infrastructure, and feature larval habitats such as rice fields and garden wells adjacent to residential, market, and commercial areas (Robert et al., 2003), as well as suburban slums and shantytowns. Limited data also suggest that certain anopheline vectors may be adapting to urban ecology. In Accra, Ghana, A. gambiae has adapted to water-filled domestic containers and polluted water habitats (Chinery, 1990). In a newly urbanized area of Kenya, A. gambiae also bred in temporary man-made sites during the rainy season (Khaemba et al., 1994).

Excluding large private operations, it is currently believed that reducing malaria in a sustained fashion by vector control alone is near impossible in areas of high and moderate transmission (Trape et al., 2002). On the other hand, areas with naturally low or unstable transmission—such as highlands, mountain areas, semi-arid regions and urbanized areas—are far more amenable to vector control. As urbanization progresses, anopheline breeding sites in African cities should decrease and localize, thus facilitating control by classical methods such as drainage, larviciding, and indoor spraying (Trape and Zoulani, 1987; Trape et al., 1992). In the future, the upside of sub-Saharan urbanization may be the creation of malaria-free zones harboring a significant proportion of a country’s population. This success could, in turn, stimulate expanding eradication efforts using vector control and other integrated interventions.

Epidemic Malaria

Malaria epidemics generally occur in regions where transmission is low or absent most of the time and populations lack protective immunity, although epidemics also can strike higher-transmission areas when there is a breakdown in health or environmental services, increasing drug resistance, or recent immigration of nonimmune individuals (e.g., laborers coming to



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